In polyurethane foam manufacturing, surfactants are required to stabilize the foam until the polymer-forming chemical reactions are sufficiently complete so that the foam is self-supporting and does not suffer objectionable collapse.
Silicone polyether surfactants for polyurethane foam manufacture are typically materials having siloxane backbones and pendant polyether groups. They are of two types, nonhydrolyzable and hydrolyzable. The nonhydrolyzable surfactants, in which the pendant polyether groups are attached to the siloxane backbone via Si--C bonds, are generally believed to provide high efficiencies but poor processing latitudes. Hydrolyzable surfactants, in which the pendant polyether groups are attached to the siloxane backbone via Si--OC bonds, are generally believed to have poor efficiencies but wide processing latitudes.